Aside from many smaller fixes and improvements to various pages, the most notable changes in man-pages-3.78 are the following:

A new execveat(2) page documents the execveat() system call that was added in Linux 3.19.

A new memfd_create(2) page documents the memfd_create() system call that was added in Linux 3.17. This page also provides an overview of the file-sealing API. The file-sealing operations themselves are documented in updates to the fcntl(2) man page.